I keep blowing up Dougnuts that go betwen the header and the CAT. They are only lasting me about a month. I'm not sure how to fix this problem. Does anyone have any ideas? I also need a place that can ship me 3 or 4 of them.
Mario

 

Ouch - I've been there before. I seem to recall that it's notoriously difficult to acquire these donut gaskets - OBX dealer support is sporadic, and SuperSprint won't ship them to OBX owners.

My shop ended up fabricating a flex joint for the OBX to prevent the gasket from slipping off - it's worked for the past 1.5 years, and I'm still running on the original donut gasket, even though it's a little dinged from the vibrations of the OBX header.

Let's hear it if you've found a replacement donut gasket for the OBX header!

 

We need to get good dimensions for this gasket. I'm sure these guys have one that will work but I don't have any numbers.

https://www.theflangeman.com/cgi-bin...K&keywords=all

 

does anyone know the size of the Mini OBX header gasket?

 

Wish I could be of help but I got a call from the shop in town where I have been taking my MCS for all my mods and they said they are having a huge issue with installation which consist of it not fitting properly to the cat and the 02 sensor/bong!!

I am now in limbo as to what to do. They say they can fix it somehow but that it takes more time and fabrications to make it work. I'm trying to keep the stock cat for emission reasons.

 

I measured mine the last time I had it off and it was 2.5" ID. I ordered the one from the link below which measures exactly the same; regretfully I have not had a chance to actually fit it to my car. For $16 it's worth a try...
Marty

http://www.hotseatperformance.com/ps...2669&CATID=249

 

It's not exact but should work in 1963-1974 Vetts used a Donut Gasket.

Part # 603-608, Exhaust Donut Gasket 2.5", each $4.99
http://www.madvet.com/shop?frame=1.39.4119

 

he found a source...

Matt

ps, if you're blowing one a month, check your engine mounts and the mounting tension. This isn't right and indicates either the engine in moving too much or that your clamping force is way to high.....

 

Agree - I have 2 years on mine / 10,000 miles on original donut.

 

The funny thing is I even have a TSW motor mount to keep things under control. The people at the muffler shop say they have never seen an exhaust get that hot! They have been saying that since my car was stock, no matter what exhaust I had on there.

 

is this something you have heard or tried?
Thank you for the link
Mario

 

Mario - one other thought, perhaps the cat/pipe piece that fits between the OBX header and your exhaust is just slightly too long - placing additional pressure on the gasket ?

I know when i first fit my OBX header and in my case re-cycled the old cat, the cat/pipe piece that went inbetween the header and the exhaust was slightly too long. The result was that it pushed my exhaust pipes further out the back and even created a rattle. When I swapped from the 1-ball to a catback, I corrected this.

Just trying to help.

 

I was able to make those adjustments with my Magnaflow at the slip joints.
The tension at the joint is key to gasket survivability.
I haven't had to replace the original donut gasket. I like the one meh found as it is closer to the original.
Have a look at my gallery pictures of the flange.

 

Good someone understood what I was trying to say .

 

Dimensionally it is perfect and looks exactly the same; if only I could find the time to check it; just coming back from vacation doesn't help though...

 

Great find meh I'm filing this away for future if I ever the need to replace mine.

http://www.hotseatperformance.com/ps...2669&CATID=249

 

I have OBX. Before installing header, I used some scotchbright and file and really smoothed and polished and deburred the surfaces which the gasket sits between. There were burrs at the edge of the swivel joint and the stampings were not real smooth. I figured it is better for the surfices to smoothly swivel than for them to abrade the gasket. check out the surfaces when you have the header disconn from the cat/catback. Also, you might drill and put cotter pins into the bolts which the springs go on so you don't have to tighten down the spring so much to keep the nuts from backing off and loosening over time. A little less pressure/wear on the gasket this way.

If your exhaust is getting so hot, maybe the cat is melting and you are building up a lot of back pressure. I know someone earlier was having problem with that - hopped up car, running too rich, causing overheat condition of cat which melted cat which caused more back pressure, more heat, more melting, etc.

 

Meh,

have you had a chance to install the gasket, does it work? I tried 2 of them a got exhaust leaks. Did not fit snug and had 2 what I think were alignment notches, I suppose for what it was intended, that created leaks. Just wondering if I was shipped something different from you.

 

How do you have the spring attached? It should be on the OUTSIDE of the flange (not in between) and you should have a longer bolt than it came with so you can allow for spring preload and double nutting the bolt. I have a picture at home, I'm at work right now. You could have them fab up a flex joint instead of the little donut thing if you really want to spend money, but for the money i'd just get a new header, the OBX is cheap, but it's not that much better than stock.

 

If your exhaust is getting that hot perhaps it's running lean? What kind of AF's do you have? Did you ever get that wideband?

 

My air/fuels are 10.7-11.3 at peak HP. I'm getting my Air/fuel gauge tomorrow from Jan. I fianlly had a custom gasket made at a muffler shop. It works great and I have had no problems since then. I also had them replace the springs, they were toast. My OBX gaskets were only lasting a month of so.

 

Hi all, I am sure this thread will always be actual...I faced the same issue with the gasket paired with the obx manifold...I guess whether the obx company has ever faced their manifold installation cause not only the gasket is the only thing not fitting properly, btw...I did replace the useless gasket paired with with a standard one for the 65 mm diameter and it did the trick...here in Poland you can buy one for mere 10 zl (2.5/3 usd).
The work that it came out is astonishing.
Here you are the pic

 

What's the manufacturer of the gasket you used? 65mm is the inner diameter, right? I found a couple of such gaskets here in Finland, but they're closer to 30€...

I'm dropping the header for starter motor replacement, so I thought I might as well replace the donut gasket while I'm taking it out. My original OBX donut gasket has been there for over 25.000km. It's not leaking, but it must be somewhat worn by now...

 

Hi, yes the inner diameter is 65mm.
Those are standard gaskets and they are made just for being settled in between the cat and the rest of the main pipe.
Here in Poland they are sold for 2.5 eur.
I ve seen something similar in Italy were I did spend most of my life...prices were 2x,3x,4x.
If you want I can buy some for you if you want, with calm
Those gaskets here have no manufacturer, they are sold as spare parts and probably they are made here in Poland.